Program for nth Catalan Number | C # program for nth Catalan Number ; Returns value of Binomial Coefficient C ( n , k ) ; Since C ( n , k ) = C ( n , n - k ) ; Calculate value of [ n * ( n - 1 ) * -- - * ( n - k + 1 ) ] / [ k * ( k - 1 ) * -- - * 1 ] ; A Binomial coefficient based function to find nth catalan number in O ( n ) time ; Calculate value of 2 nCn ; return 2 nCn / ( n + 1 ) ; Driver code
using System ; class GFG { static long binomialCoeff ( int n , int k ) { long res = 1 ; if ( k > n - k ) { k = n - k ; } for ( int i = 0 ; i < k ; ++ i ) { res *= ( n - i ) ; res /= ( i + 1 ) ; } return res ; } static long catalan ( int n ) { long c = binomialCoeff ( 2 * n , n ) ; return c / ( n + 1 ) ; } public static void Main ( ) { for ( int i = 0 ; i < 10 ; i ++ ) { Console . Write ( catalan ( i ) + " ▁ " ) ; } } }